Adjustable frame for thin sheet electrodes

ABSTRACT

An electrode assembly includes an adjustable frame having a thin sheet electrode mounted therewithin. The frame comprises parallel side bars and end members extending therebetween, with at least one of the end members being slidably engageable with the side bars to vary the area defined within the frame. An electrically conductive connector is provided on the electrode for connection to a current source, and means is included to support the assembly within a plating tank.

s E D O R T C E L E Rm JM )S GN NM w T R Y O Y. F R E M GM F E L B A T s U J D A July 1s, 1972 2 Sheets-Sheet l Filed Aug. 19, 1970 FIGS In ven for Geary@ Pal/ You/157, Jr.

@y W921i j 567% orney July 1s, 1972 I G. Rz YoU-NG, JR

ADJUSTABLE FRAME vFOR THIN SHEET ELECTRODES Filed Aug. 19, 1970 2 Sheets-Sheet [Nye/Mor Geo/ya falla/z Younyllr.

fea/MN United States 'Patent Officey 3,677,929 Patented July 18, 1972 3,677,929 ADJUSTABLE FRAME FOR THIN SHEET ELECTRODES George Ralph Young, Jr., Woodbury, Conn., assigner to American Chemical & Refining Company Incorporated, Waterbury, Conn.

Filed Aug. 19, 1970, Ser. No. 65,117 Int. Cl. B01r 3/ 04; C23b 5/74 U.S. Cl. 204-286 12 Claims ABSTRACT OF THE DISCLOSURE BACKGROUND OF THE INVENTION Thin sheet solid and expanded mesh electrodes are employed in an variety of plating operations because they provide good electrode distribution without utilizing undue amounts of electrode material. They are particularly usef-ul as anodes because the large surface area provided results in desirably uniform deposits of plated metal. Electrodes of this type are used in a variety of electrodeposition processes, and they may be fabricated from a wide variety of materials; they are especially well suited for use in depositing precious metals, such as gold, silver, platinum, palladium and the like.

To attain the greatest levels of eiciency and effectiveness with such electrodes it is important that they be maintained in a relatively planar configuration during the plating operation. However, due to their relatively small mass and large area, these electrodes have a considerable tendency to curl, oat or Otherwise be disturbed during plating, and the problem becomes more acute as agitation of the bath is increased. In an eiort to counteract these eiects, a heavy object (typically a brick) is often attached to the lower end of the electrode. This practice is undesirable for a number of reasons including the undue stress upon the electrode that results from the concentration of force over a limited area thereof, the possibility of contamination of the bath by the introduction of foreign matter, etc.

Accordingly, it is an object of the present invention to provide a novel electrode assembly mounting of a thin sheet electrode in a relatively planar conguration in an electroplating bath.

It is also an object of the invention to provide such an assembly wherein the electrode is maintained in a substantially vertical position even when the bath is well agitated.

Another object is to provide such an assembly that includes a frame of relatively simple design and inexpensive construction and that is readily adjustable to accommodate electrodes of various dimensions.

SUMMARY OF THE INVENTION It has now been found that the foregoing and related objects can be readily attained in an electrode assembly including an adjustable frame which comprises a pair of relatively rigid, substantially parallel side bars and a pair of relatively rigid end members extending therebetween. At least one of the end members is slidable on the side bars for variation of the spacing from the other end member, and disengageable means is provided for securing the slidable end member in a plurality of spaced, parallel positions along the length of the side bars. If so desired, bath end members may be slidable for such variation. The frame has means on the end members and side bars for mounting a thin sheet electrode within the area enclosed thereby, and the assembly includes such an electrode that is so mounted. An electrically conductive connector on the electrode permits connection to a current source and means for supporting the assembly within a plating tank is provided.

In the preferred embodiments, the opposing surfaces of the side bars are longitudinally slotted to provide the mounting means thereon. The electrode is constructed with parallel side edges, so that marginal portions therealong are received in the longitudinal slots to mount the electrode in cooperation with the mounting means on the end members.

In such a case, at least the slidable end` member may have a tongue at each end thereof that is slidably received in the slots of the side bars. Preferably, the portions of each of the side bars defining the sides of the slot therein may be flexed inwardly under clamping pressure, in which event the securing means desirably includes a clamp bearing upon the side bars and closing the flexible portions thereof -upon the tongue received therein.

Alternatively, at least the slidable end member of the frame may have a transverse aperture adjacent each of its ends, with a pin hole extending inwardly from each end and communicating with the aperture thereat. In such a construction, each of the side bars is provided with a plurality of transverse notches at spaced locations along its length, and the securing means will then include a pin seated in each of the pin holes. One of the side bars is inserted through each of the apertures in the slidable end member, and the pins are engaged in notches of the side bars to secure the slidable end member in a desired position along the length of the side bars.

The mounting means on the end members may include a plurality of slotted elements projecting inwardly therefrom, or an inner surface of each of the end members may be longitudinally slotted to provide the mounting means thereon; in either case, marginal portions of the electrode are received in the slots for mounting within the frame. Most desirably, the electrode has at least one elongated member secured thereto and extending outwardly from one end thereof beyond the adjacent end member to provide support means for the assembly. Moreover, the elongated member may be electrically conductive and in electrical contact with the electrode to provide the necessary connector eas well as support means. The side bars may extend outwardly beyond the end member opposite the previously-mentioned adjacent end member, so that the assembly may be supported from an associated overhead structure by the support means, and may rest upon the bottom wall of the associated plating tank with the ends of the side bars in contact therewith. It is particularly preferred that the electrode referred to be an anode.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of an electrode assembly embodying the present invention, supported upon a fragmentarily illustrated busbar;

FIG. 2 is a side elevational view thereof, with a portion at the bottom of the assembly, along line 2 2 of FIG. l shown in section;

FIG. 3 is a sectional view thereof along line 3-3 of FIG. 2;

FIG. 4 is a fragmentary perspective view of the upper right hand corner of the assembly, drawn to an enlarged scale and with the securing pin removed from the pin hole in the end member;

FIG. is a front elevational view of the assembly of FIG. l in inverted position and supported upon a busbar with the ends of the side bars resting upon the bottom wall of a plating tank;

FIG. 6 is a front elevational view of another electrode assembly embodying the invention;

FIG. 7 is a side elevational view of the assembly of FIG. 6;

FIG. 8 is a plan view thereof; and

FIG. 9 is an exploded, fragmentary, perspective view of the upper right-hand corner of the embodiment of FIGS. 6-8.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS Turning now in detail to FIGS, 1-5 of the appended drawings, therein illustrated is an electrode assembly embodying the present invention and including a frame, generally designated by the numeral 10, having a pair of elongated side bars 12 and elongated upper and lower end members 14, 16 respectively. The end members 14, 16 have transverse apertures 18 adjacent each of their ends, and they have pin holes 20 extending generally axially inwardly from the ends thereof, so that the apertures 18 and pin holes 20 intersect. Each side -bar 12 has a series of three axially spaced notches 22 adjacent one end thereof, and a single notch 22 adjacent the opposite end, as is best seen in FIG. 2. The side bars 12 are inserted through the apertures 18, and are secured in the position desired by engagement of the pins 24 seated in the holes 20 within appropriate notches 22.

Each of the end members 14, 16 has a transversely extending hole 26 spaced from each end thereof, in which is seated an inwardly extending supporting peg 28. The end surface of each of the pegs 28 extending inwardly of the frame has a transverse slot 30, and the side bars 12 have longitudinal slots 32 in their inner surfaces extending along the entire length thereof. An expanded mesh electrode 34 is mounted between the side bars 12 with marginal side portions thereof seated in the slots 32. Marginal end portions of the electrode 34 are seated in the slots 30 of the pegs 28 to maintain the electrode 34 in position, and to prevent longitudinal bending thereof such as would allow disengagement of the side portions from the slots 32. rThe electrode 34 is also provided with elongated ribs or corrugations 36 along its side margins to enhance the rigidity thereof and prevent inadvertent disengagement from the pegs 28.

The assembly is supported upon an overhead busbar 38 `by a pair of straps or hangers 40. The hangers 40 have a reversely bent upper end portion 42 by which they are tted over the busbar 38, and the lower ends 44 thereof are welded or otherwise securely attached to the electrode 34. The end member 14 has a pair of short slots 46 through which the hangers 40 pass to ensure support of the assembly in a desirable manner.

In FIG. 5, the sidebars 12 are inverted from the position shown in FIGS. 1-4. As a result, they extend downwardly, in a direction opposite to the hangers 40 and into contact with the bottom wall 46 of a plating tank (only schematically illustrated by the bottom Wall 48) to provide added support for the assembly in a preferred manner.

Turning now to the embodiment of FIGS. 6-9, the electrode assembly is similar to that of FIGS. 1-5, and the frame, generally designated by the numeral 50, has a pair of side bars 52 and end members S4, 55. The side bars 52 each have a longitudinal slot 56 provided in the inner surface thereof and extending along the length thereof, and the wall portions S8 of the side bars 52 deiining the slots S6 are relatively liexible due to the relatively thin cross section and bifurcated construction. The end members 54, 55 also have slots 60 that extend along their inside surfaces, and a tongue 62 projects axially from each end of the end members 54, 55.

As was the case in the embodiment of FIGS. l5, an

electrode 64 (in the instance of a solid, non-expanded construction) has its marginal side portions engaged in the slots 56 of the side bars 52. In the present embodiment, the marginal end portions of the electrode 64 are engaged in the slots 60 of the end members 54, 55 and the side bars 52 and end members S4, 55 are assembled with the tongues 62 engaged in the slots 56. A spring clip 66 is engaged over the side bars 52 at each location at which a tongue 62 of an end member 54, 5S enters the slot 56 therein, and the clips 66 exert suicient clamping pressure to deflect the portions 5S inwardly to clamp the end members 54, 55 in the position desired. A single hanger 68 is welded to the electrode 64 and passes through the translverse slot 70 in the end member 54, to support the assembly upon a busbar in the manner previously described.

As has been discussed, the assembly of the present invention includes an expanded or solid electrode, and it should therefore be understood, as used herein, that the phase thin sheet electrode encompasses elements having a solid, expanded or perforated construction. Such electrodes usually have a tendency to oat, curl or to otherwise be rendered non-planar under the conditions of operation. The overall thickness of the electrodes will usually be in the range of about 0.0l-0.l inch; the invention affords the greatest benefits when the electrode is less than about 0.0625 inch thick.

Electrodes of this type are most often provided in only a few standard widths, such as 4, 6, and 8 inches. However, the lengths thereof vary considerably and are frequently tailored to the requirements of each customer and his electroplating equipment; typically, the length of the electrode will range from about 9 to 24 inches. Accordingly, it is most important that the frame be provided with at least one end member that is adjustable to accommodate various lengths of electrodes, although both ends may be adjustable for greater variation or to permit alteration of the depth at which the electrode is submerged in the bath. From the standpoint of achieving the most secure mounting of the electrode, the type 0f frame depicted in FIGS. l-5 of the drawings may be preferred due to its positive locking features. However, the frame shown in FIGS. y6-9 permits a much wider lattitude of variation (albeit with some sacrice in the firmness of mounting) so that electrodes in all lengths between the extreme positions of the frame may be supported thereby.

The configuration of the end members and of the side bars may vary considerably from those shown in the dra-W- ings, and cross sections other than round and square may prove appropriate in some instances. However, since round and rectangular stock materials are usually the most readily available, it may be most economical and convenient to design the frme so as to employ them. Similarly, the configuration of any pins, pegs or other elements employed in the frame may vary from those depicted, and pins such as those shown in the end members of FIGS. .1 5 could be substituted for the slots in the side bars to receive the marginal portions at the sides of the electrodes. It will be apparent that the slots in the side bars of the frame of FIGS. 6-9 serve not only to accommodate the edges of the electrode, but also to provide wall portions defining the slots which are deflectable; in full section, the side bars must at least be suiciently rigid to provide the necessary level of support for the electrode. If so desired, the tongue provided at each end of the end members may have an enlarged edge portion for engagement in an appropriately dimensioned and configured keyway, to enhance the interengagement between the side bars and end members.

The hangers illustrated in the drawings constitute a particularly preferred type of support means for the assembly because, when constructed of an electrically conductive material, they may also furnish the electrical connection necessary between the electrode and the power source. Nevertheless, the support means may take other forms and may be secured to the frame rather than to the electrode itself; in such a case, an independent conductor attached to the electrode would also be provided.

Although the pegs utilized in the embodiment of FIGS. lprovide a simple and inexpensive way of interengaging the side bars and end members, other conventional means may -be substituted therefor. For example, a spring-loaded detent may be provided on one member to cooperate with a series of indentations in the associated member, to effect interengagement in `various positions. As regards the clamps used in the assembly of FIGS. 6-9, they may be of the spring-type shown, or they may for example, employ threaded elements capable of developing a higher level of force, and thereby greater security, eg., the clamp may be a modified C-clamp or similar device.

Although protectively coated metallic elements may be employed for the frame portion of these assemblies, it is preferred that nonmetallic elements be used, both from the standpoint of economics and also to minimize the prospects of contamination of the bath. Furthermore, although the frame may be made of wood or other natural materials, synthetic polymers will in most instances provide the most appropriate materials for construction of the frame elements because they may be relatively light in weight, readily adjustable, easily fabricated and resistant to attack by the constituents of the bath. The selection of the best material in a given instance will depend primarily upon economics and the nature of the bath, and exemplary suitable materials include polyethylene, polypropylene, natural and synthetic rubbers, fiber glass, reinforced plastics such as polyesters and polyolens, etc. Regardless of the particular material used for the frame, it should be apparent that it must be constructed of a material having a sufiiciently high density or otherwise weighted so that the frame itself does not oat in the bath.

Thus, it can be seen that the present invention provides an electrode assembly mounting a thin sheet electrode in a relatively planar configuration in an electroplating bath, and the electrode may be maintained in a substantially vertical position thereby. The assembly includes a frame that is readily adjustable to accommodate electrodes of various dimensions, and it may be of simple design and inexpensive construction.

Having thus described the invention, lI claim:

1. In an electrode assembly, an adjustable frame comprising a pair of relatively rigid, substantially parallel side bars, a pair of relatively rigid end members extending between said side bars with at least one of said end members being slidable on said side bars for variation of the spacing from the other one thereof, disengageable means for securing said one end member in a plurality of spaced, parallel positions along the length of said side bars, and means on said end members and side bars for mounting a sheet electrode inwardly thereof and within the area enclosed thereby; an integral sheet electrode which is thin in comparison to its length and breadth mounted by said mounting means within said area of said frame; an electrically conductive connector on said electrode for connection to a current source; and means for supporting said assembly within a plating tank.

2. The assembly of claim 1 wherein said mounting means on said side bars includes longitudinal slots in the opposing surfaces of said side bars and wherein said electrode has parallel side edges, marginal portions along said side edges thereof being received in said longitudinal slots to mount said electrode in cooperation with said mounting means on said end members.

3. The assembly of claim 2 wherein at least said one end member has a tongue at each end thereof slidably received in said longitudinal slots of said side bar.

4. The assembly of claim 3 wherein the portions of each of said side bars defining the sides of said slots therein may be flexed inwardly under clamping pressure, and wherein said securing means includes a clamp bearing upon said side bar and closing said portions thereof upon said tongue received therein.

r5. The assembly of claim `1 wherein at least said one end member has a transverse aperture adjacent each' of its ends and a pin hole extending inwardly from each of said ends and communicating with said aperture adjacent thereto, wherein each of said side vbars has a plurality of transverse notches at spaced locations along the length thereof, and wherein said securing means includes a pin seated in each of said pin holes, one of said side bars being inserted through each of said apertures in said one end member with said pins being engaged in notches of said side bars to secure said one end member in a desired position along the length of said side bars.

6. The assembly of claim 1 wherein said mounting means on said end members includes a plurality of slotted elements proejcting inwardly therefrom, marginal portions of said electrode Ibeing received therein for mounting within said frame.

7. The assembly of claim 1 wherein an inner surface of each of said end members is longitudinally slotted to provide said mounting means, marginal portions of said electrode being received therein for mounting within said frame thereon.

`8. The `'assembly of claim 1 wherein both of said end members are slidable on said side bars for variation of the spacing therebetween.

9. The assembly of claim 1 wherein said electrode has at least one elongated member secured thereto and extending outwardly from one end thereof beyond the adjacent end member to provide said support means for said assembly.

10. The assembly of claim 9 wherein said elongated member is electrically conductive and is in electrical contact with said electrode to provide said connector as well as said support means.

11. The assembly of claim 9 wherein said side bars extend outwardly beyond the end member opposite to said adjacent end member, so that said assembly may be supported from an associated overhead structure by said support means and may rest upon the bottom wall of the associated slotting tank with the end of said side bars in contact therewith.

12. The assembly of claim 1 wherein said electrode is an anode.

References Cited UNITED STATES PATENTS 1,354,234 9/ 1920 Blaetz 204-297 R 2,044,431 6/ 193 6 Harrison 204-297 R 2,967,814 l/ 1961 Tuwiner 204-284 1,470,577 10/ 1923 Liebknecht 204-284 2,190,440 2/ 1940 Beebe 204-297 =R FOREIGN PATENTS 118,711 1/ 1927 Switzerland 204-286 JOHN H. MACK, Primary Examiner R. J. FAY, Assistant Examiner U.S. Cl. X.R. 204-284, 297 R 

